1. Technical Field
This invention relates to center fold hangar doors sometimes call canopy-type doors as used in buildings having large openings such as airplane hangars.
2. Description of the Prior Art
Due to the large surface area of large center fold hangar doors, one of the problems associated with their use has been to adequately stabilize the door against wind gusts particularly when the door is in fully closed position. Extensible diagonal bracing struts have been used for this purpose as seen for example in U.S. Pat. Nos. 2,936,830 and 4,124,055. Locking devices attempting to secure such door assemblies in vertically superimposed relation are disclosed in U.S. Pat. Nos. 1,841,185, 3,024,838 and 3,504,729.
The present invention eliminates the problems that have been inherent in the prior art devices by providing a structure which movably positions telescopically arranged tubular members secured to the upper and lower door portions in a manner that requires relative movement of the tubular members when the upper and lower door portions move away from a vertical superimposed closed position and prevents such movement by selectively locking the tubular members to one another when the upper and lower portions of the door are in closed superimposed position.